Block and tackle window balance systems, of which Dinsmore U.S. Pat. No. 3,358,404 is an example, have used conventional pulley blocks straddling a pair of pulleys mounted on an axle extending between the sides of the pulley block. This requires threading a cord through the space between the pulley block and a pulley periphery as the cord is reeved over each of at least four pulleys.
I have found a better way of mounting pulleys in a block and tackle window balance system. My pulley mount is less expensive, uses pulley mounting plates that also serve other functions, such as connecting to a channel and coupling to a spring, and speeds up the assembly time by allowing the cord to be looped rapidly over each pulley periphery, instead of being threaded through pulley blocks. My pulley mount thus achieves economy of manufacture and assembly combined with durable and reliable operation.